In:
Cancer Research, American Association for Cancer Research (AACR), Vol. 70, No. 8_Supplement ( 2010-04-15), p. 3871-3871
Abstract:
Circadian clocks are found in most organisms and influence a large array of cellular, physiological and behavioral processes. Consequently, disruption of circadian function results in severe dysfunctions and has been associated with various pathologies including cancer. Recent findings revealed intriguing links between the circadian system and another highly conserved biological system, the DNA damage response (DDR). Upon DNA damage, eukaryotic cells activate a complex signaling network to regulate cell cycle checkpoint arrest and/or apoptosis. At the core of the DDR are the ATM, ATR and DNA-PK kinases, which phosphorylate numerous downstream targets on preferred SQ motifs. We previously showed that the key circadian factor, Per1, associates with ATM and sensitize cells to DNA-damage induced apoptosis. In a recent screen, human Per1 Ser1263 was identified as a potential substrate for ATM/ATR. Per1 Ser1263 is part of a SQ motif conserved among mammalian Per1 proteins. To confirm that Per1 is phosphorylated on this site, we mutated murine Per1 Ser1264 (corresponding to human Ser1263) to alanine. 293T and HCT116 cells were transfected with either wild-type (WT) or S1264A mutant (SA) myc-tagged Per1 and treated with DNA-damaging agents. Western blot analysis demonstrated that Per1WT was recognized by phospho-specific SQ antibodies, while Per1SA was not. Furthermore, Per1 phosphorylation was significantly stronger in the treated cells. Interestingly, Per1 remained phosphorylated in ATM deficient cells. In contrast, silencing of ATR by shRNA in 293T cells attenuated Per1 phosphorylation. Immunoprecipitations experiments showed that both overexpressed and endogenously expressed Per1 associate with ATR. To examine the functional significance of Per1 phosphorylation, we transfected SKOV3 cells with either myc-Per1WT or myc-Per1SA, and monitored their cell-cycle progression and apoptotic response after DNA damage. Compared to control SKOV3 treated cells, Per1WT expression resulted in significant increased numbers of G2/M arrested and apoptotic cells. This increase was diminished by Per1S1264A mutation. Our findings implicate Per1 as an important ATM/ATR substrate, and emphasize the significance of proper circadian regulation to cell survival upon exposure to genotoxic stress. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3871.
Type of Medium:
Online Resource
ISSN:
0008-5472
,
1538-7445
DOI:
10.1158/1538-7445.AM10-3871
Language:
English
Publisher:
American Association for Cancer Research (AACR)
Publication Date:
2010
detail.hit.zdb_id:
2036785-5
detail.hit.zdb_id:
1432-1
detail.hit.zdb_id:
410466-3
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